Dave Butler wrote in
news:1103570747.387686@sj-nntpcache-5:

You didn't mention: (since this is a Mooney) check or replace the
o-rings in the fuel filler caps frequently, perhaps twice as often as
required by the AD. Also check for corrosion of the cap mechanism
preventing the o-rings from sealing properly.

Just prior to the rainy season this year I replaced all four o-rings. One
big one around the cap and the little one in the middle of the cap shaft.
You could really see the old ones were very stiff and brittle. I hear you
should replace these a couple of times a year. I think they only cost
about $8 for all four and I put them on myself in about 10 minutes.